This disclosure relates to a medical device and more particularly to implantable neurological electrical stimulators and implantable electrical stimulation leads.
The medical device industry produces a wide variety of electronic and mechanical devices for treating patient medical conditions such as pacemakers, defibrillators, neurostimulators, and therapeutic substance delivery pumps. Medical devices can be configured to be surgically implanted or connected externally to the patient receiving treatment. Clinicians use medical devices alone or in combination with therapeutic substance therapies and surgery to treat patient medical conditions. For some medical conditions, medical devices provide the best and sometimes the only therapy to restore an individual to a more healthful condition and a fuller life. One type of medical device is an implantable neurological stimulation system that can be used to treat conditions such as pain, movement disorders, pelvic floor disorders, gastroparesis, and a wide variety of other medical conditions. The neurostimulation system typically includes a neurostimnulator, a stimulation lead, and an extension such as shown in Medtronic, Inc. brochure xe2x80x9cImplantable Neurostimulation Systemxe2x80x9d (1998).
Previous extensions are typically formed using a solid conductor formed from a material that is a reasonably good compromise between the mechanical properties required to form electrical connections and the conductive properties required to efficiently conduct the stimulation signal from the neurostimulator to the stimulation lead. The compromise of material used in a solid conductor results in higher impedance than is desired. The extension""s higher impedance than desired can result in increased power consumption and decreased battery life. An example of an extension that uses a solid conductor is shown in Medtronic, Inc. brochure xe2x80x9cModel 7495 Extension Kit for Stimulation of the Brain, Spinal Cord, or Peripheral Nervesxe2x80x9d (2000). An example of a low impedance lead used for cardiac pacing and defibrillation typically having only one or two conductors is shown in U.S. Pat. No. 5,330,521 xe2x80x9cLow Resistance Implantable Electrical Leadsxe2x80x9d by Cohen (Jul. 19, 1994).
For the foregoing reasons, there is a need for a low impedance extension that decreases power consumption and has many other improvements.
A low impedance extension for an implantable neurological electrical stimulator embodiment reduces energy consumption and has many other improvements. The low impedance extension has a conductor composed of an outer surface and an inner core. The outer surface has an outer impedance and the inner core has a core impedance that is substantially lower than the outer impedance. The low impedance extension has an extension proximal end, an extension distal end and an extension body. The extension proximal end has at least one proximal contact coupleable to an implantable neurostimulator connector block and an extension distal end having at least one extension distal contact coupleable to the lead proximal contact. The extension conductor is contained in the extension body to electrically connect the extension distal contact with the extension proximal contact. Many embodiments of the low impedance extension are possible.